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554edb23ff
Similar to various other bugs in this area, some expm1 implementations do not raise the underflow exception for subnormal arguments, when the result is tiny and inexact. This patch forces the exception in a similar way to previous fixes. (The issue does not apply to the ldbl-* implementations or to those for x86 / x86_64 long double. The change to sysdeps/ieee754/dbl-64/wordsize-64/e_cosh.c is one I missed when previously fixing bug 16354; the bug in that implementation was previously latent, but the expm1 fixes stopped it being latent and so required it to be fixed to avoid spurious underflows from cosh.) Tested for x86_64 and x86. [BZ #16353] * sysdeps/i386/fpu/s_expm1.S (dbl_min): New object. (__expm1): Force underflow exception for arguments with small absolute value. * sysdeps/i386/fpu/s_expm1f.S (flt_min): New object. (__expm1f): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/dbl-64/s_expm1.c: Include <float.h>. (__expm1): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/flt-32/s_expm1f.c: Include <float.h>. (__expm1f): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/dbl-64/wordsize-64/e_cosh.c (__ieee754_cosh): Check for small arguments before calling __expm1. * math/auto-libm-test-in: Do not mark underflow exceptions as possibly missing for bug 16353. * math/auto-libm-test-out: Regenerated.
132 lines
3.4 KiB
ArmAsm
132 lines
3.4 KiB
ArmAsm
/* ix87 specific implementation of exp(x)-1.
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Copyright (C) 1996-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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Based on code by John C. Bowman <bowman@ipp-garching.mpg.de>.
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Corrections by H.J. Lu (hjl@gnu.ai.mit.edu), 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* Using: e^x - 1 = 2^(x * log2(e)) - 1 */
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#include <sysdep.h>
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#include <machine/asm.h>
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.section .rodata
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.align ALIGNARG(4)
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.type minus1,@object
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minus1: .double -1.0
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ASM_SIZE_DIRECTIVE(minus1)
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.type one,@object
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one: .double 1.0
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ASM_SIZE_DIRECTIVE(one)
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.type l2e,@object
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l2e: .tfloat 1.442695040888963407359924681002
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ASM_SIZE_DIRECTIVE(l2e)
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.section .rodata.cst4,"aM",@progbits,4
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.p2align 2
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.type flt_min,@object
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flt_min: .byte 0, 0, 0x80, 0
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ASM_SIZE_DIRECTIVE(flt_min)
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#ifdef PIC
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#define MO(op) op##@GOTOFF(%edx)
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#else
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#define MO(op) op
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#endif
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.text
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ENTRY(__expm1f)
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movzwl 4+2(%esp), %eax
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xorb $0x80, %ah // invert sign bit (now 1 is "positive")
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cmpl $0xc2b1, %eax // is num >= 88.5?
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jae HIDDEN_JUMPTARGET (__expf)
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flds 4(%esp) // x
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fxam // Is NaN, +-Inf or +-0?
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xorb $0x80, %ah
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cmpl $0xc190, %eax // is num <= -18.0?
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fstsw %ax
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movb $0x45, %ch
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jb 4f
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// Below -18.0 (may be -NaN or -Inf).
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andb %ah, %ch
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#ifdef PIC
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LOAD_PIC_REG (dx)
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#endif
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cmpb $0x01, %ch
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je 5f // If -NaN, jump.
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jmp 2f // -large, possibly -Inf.
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4: // In range -18.0 to 88.5 (may be +-0 but not NaN or +-Inf).
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andb %ah, %ch
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cmpb $0x40, %ch
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je 3f // If +-0, jump.
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#ifdef PIC
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LOAD_PIC_REG (dx)
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#endif
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fld %st
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fabs
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fcoms MO(flt_min)
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fstp %st
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fnstsw
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sahf
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jae 5f
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subl $4, %esp
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cfi_adjust_cfa_offset (4)
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fld %st(0)
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fmul %st(0)
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fstps (%esp)
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addl $4, %esp
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cfi_adjust_cfa_offset (-4)
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ret
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5: fldt MO(l2e) // log2(e) : x
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fmulp // log2(e)*x
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fld %st // log2(e)*x : log2(e)*x
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// Set round-to-nearest temporarily.
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subl $8, %esp
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cfi_adjust_cfa_offset (8)
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fstcw 4(%esp)
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movl $0xf3ff, %ecx
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andl 4(%esp), %ecx
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movl %ecx, (%esp)
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fldcw (%esp)
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frndint // int(log2(e)*x) : log2(e)*x
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fldcw 4(%esp)
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addl $8, %esp
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cfi_adjust_cfa_offset (-8)
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fsubr %st, %st(1) // int(log2(e)*x) : fract(log2(e)*x)
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fxch // fract(log2(e)*x) : int(log2(e)*x)
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f2xm1 // 2^fract(log2(e)*x)-1 : int(log2(e)*x)
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fscale // 2^(log2(e)*x)-2^int(log2(e)*x) : int(log2(e)*x)
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fxch // int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fldl MO(one) // 1 : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fscale // 2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fsubrl MO(one) // 1-2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fstp %st(1) // 1-2^int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fsubrp %st, %st(1) // 2^(log2(e)*x)
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ret
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2: fstp %st
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fldl MO(minus1) // Set result to -1.0.
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3: ret
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END(__expm1f)
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weak_alias (__expm1f, expm1f)
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